A method to reconstruct an image by utilizing a plurality of projection data items acquired with X-rays that pass through the same pixel location in the same scan field while being transmitted along different paths with a scanner gantry set at the same view angle or an opposite view angle. A helical scan is performed in order to acquire projection data. Two or more projection data items acquired with X-rays that pass through a pixel location Q in the scan field while being transmitted along different paths with the scanner gantry set at the same view angle are synthesized in order to produce reconstruction projection data. A CT image is reconstructed based on the reconstruction projection data.